Reviewed by USGSAlaska112y ago
M7.4 earthquake 133 km WNW of Nikolski, Alaska
Tuesday, April 18, 1916, 04:01:49 UTC · 53.442°N, 170.668°W
A magnitude 7.4 earthquake struck 133 km WNW of Nikolski, Alaska on Tuesday, April 18, 1916, 04:01:49 UTC, at a depth of 140.0 km (intermediate). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.
- Magnitude
- 7.4
- Major · mB
- Depth
- 140 km
- Intermediate
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquake
In context
How big was it, and why here?
Energy released
1.9 megatons of TNT
That is about 126 times the Hiroshima bomb. It released about 3,981 times the energy of a magnitude 5.0.
Tectonic setting
218 km
from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: intermediate
140 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
Did You Feel It?
Where it was felt
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
I felt it — report to USGS ↗USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 200 km
USGS has not published any M2.5+ earthquake within 200 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 6 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 6.7103 km SE of Nikolski, AlaskaFebruary 20, 1916 · 235 km SE of this epicenter
- 6.6135 km SW of Nikolski, AlaskaDecember 23, 1906 · 166 km S of this epicenter
- 6.596 km SSE of Nikolski, AlaskaSeptember 8, 1909 · 213 km SE of this epicenter
- 6.358 km SE of Nikolski, AlaskaJanuary 12, 1907 · 190 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 6 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 223 km away
Limited damage (under $1M)tsunami
- 1902M7.8
Aleutian Islands: Fox Islands
1 Jan 1902 · 242 km away
- 1907M7.8
Aleutian Islands
2 Sep 1907 · 114 km away
- 1916M7.5
Aleutian Islands: Fox Islands
18 Apr 1916 · 47 km away
- 1872
Aleutian Islands: Fox Islands
23 Aug 1872 · 201 km away
tsunami
- 1878
East Aleutian Islands
29 Aug 1878 · 283 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.